The Vortech V3 is a killer little blower it can put out more then a stock LS3 can handle. Headers and a 3.33 pulley will put you at 600rwhp. The brackets will let you swap in a V7(YSi) if you decide to forge the motor later.
BUT ECS has a very nice set up with the NOVI 1500 that will also take the V7(YSi). ECS uses a Restricter plate on the base setup that lets it build a lot of boost in the lower RPMs to give a more HP/Torque down low but keeps it from over boosting the stock motor at high RPMs.